Effect of Intrathecal Bupivacaine Temperature Variation on Prophylaxis of Shivering in Urologic Patients Undergoing Spinal Anesthesia

BACKGROUND: Postspinal shivering is a frequent complication of spinal anesthesia (SA) and is particularly relevant in urological procedures, where perioperative heat loss can be exacerbated by irrigation fluids. Modifying the temperature of the intrathecal local anesthetic may affect thermoregulatory responses and the properties of the blockade. METHODS: This prospective, randomized, double-blind, controlled trial was conducted in 96 patients (ASA I-II, aged 18-60 years) undergoing elective urological procedures under SA. Participants received intrathecal hyperbaric bupivacaine 0.5% (15 mg) combined with fentanyl 25 μg at one of three temperatures: 4°C (cold; n = 32), 24°C (room; n = 32), or 37°C (warm; n = 32). Shivering was graded using the validated Crossley and Mahajan scale. The primary endpoint was the incidence of clinically significant shivering (Grade ≥ 3) throughout the observation period, evaluated at 10-min intervals. RESULTS: Cold bupivacaine demonstrated a significantly higher incidence of clinically significant shivering (Grade ≥ 3) (81.3%) compared with the room-temperature (34.4%) and warm (25%) groups (p < 0.001). The post hoc analysis showed that the difference between the room-temperature and warm groups was not significant. Pharmacological intervention requirements were substantially elevated in the cold group (43.8%, 15.6%, 15.6%; p = 0.01). Warm bupivacaine accelerated sensory and motor block onset (p = 0.001) while reducing residual motor blockade. CONCLUSION: Warmed intrathecal bupivacaine significantly reduces PSS incidence and severity while optimizing block characteristics without compromising safety in urological patients. Trial Registration: ClinicalTrials.gov identifier: NCT07081516.